Analysis Of Heart Sound Signal Characteristics Based On Cardiac Hemodynamics

Heart sound is one of the most important physiological signals to evaluate human cardiac function.As the heart sound signal is weak and contains a strong noise,the analyzing of characteristics of heart sounds is very important for early diagnosis and treatment of heart diseases.This dissertation studies the denoising of heart sound signal and the method of envelope extraction.On this basis,the effective time period of the signal is detected,the function index of the heart is calculated and the power spectrum analysis is carried out.In this paper,the theoretical basis of heart sound signal processing method has been studied based on the medical principle of heart sound signal.A new method is designed for the key steps of the heart sound signal processing.The wavelet decomposition method is used for denoising,and the heart sound signal is extracted by the method of short time average energy.Finally,the feature value of the heart sound signal has been extracted by using the dual-threshold segmentation method.The wavelet transform is used to decompose the signal into 8 layers,and each layer is de-noised by soft threshold,then the denoised heart sound signal is obtained after the signal reconstructed by the threshold processing layer The feature envelope is extracted by calculating the short time energy of the signal.The threshold point of the first heart sound(S1)and the second heart sound(S2)is determined by a double threshold detection algorithm.At last,400 heart sound signals are processed in the heart sound database,as well as the synchronous ECG signals are used for calibration and detection.The experimental results show that this method can be used in the effective period detection of heart sound signals.On the basis of the detection of the eigenvalues of the heart sound signals,the cardiac function indexes of the heart sound signals are calculated with reference to the ECG signals,including the amplitude ratio of the first heart sound and the second heart sound,the time ratio of the diastolic and systolic time,and the heart rate calculation,and the positive abnormal heart sound signals are identified according to the cardiac function index.Combining the temporal characteristics of heart sounds,we further analyze the spectrum characteristics of heart sounds,and extract the frequency domain eigenvalues of signals.The experiment shows that the analysis of the normal heart sound and abnormal heart sound from the time and frequency domain characteristics has obvious difference,which is of greatsignificance to the heart auscultation and provides help for the prevention and treatment of heart disease.